It’s a windy and cold Thursday and we have to watch for some beefy snow showers and squalls this morning. This will be followed by subzero temperatures tonight. Stay up on the latest short term weather by checking out the social media outlets (mine and Jess’s).

This post will focus on the Sunday-Monday snow threat. We plan on looking at the latest models before putting accumulations in our official forecast this afternoon, but this post will give you a peek “behind the curtain”.

First of all, it’s important to note that the disturbance largely responsible for the snow threat is still over the Pacific Ocean. Computer models will be more trustworthy once the system is over land, since there will be more data available for them to analyze. Here’s an animation showing the system crashing into California and then coming east. Click to animate:

The colors represent the “vorticity” or spin in the atmosphere at about 18,000 feet. Spinning air parcels at that level aid in air rising and clouds/precipitation forming.

Snow will get going late Saturday night and continue at varying intensity Sunday. There will be times Sunday that it is not snowing that hard at all. We are still too far out to pinpoint when snow is likely to be lighter/heavier during Sunday.

We are pretty confident the worst of this storm will be Sunday NIGHT and early Monday. Here’s a few computer model snapshots at 1am Monday morning:

GFS:

European:

Canadian:

The Canadian looks a bit different than the other two; snow is lighter at this time step on the Canadian. This is an outlier at the moment.

One thing we look at when figuring out how hard precipitation will be falling is the “vertical velocity” at about 10,000 feet. It shows how quickly the air is rising. The faster it is rising, the heavier the precipitation is likely to be. Here’s the GFS vertical velocity map at 1am Monday:

It has the best upward motion south of Rt. 30, but still looks decent for most of the Valley.

How Much Snow?? That is the question.

Let’s see what the current models say. First, the GFS:

A general 6-10″ range for the WFMJ viewing area.

The Canadian: Looks like a range of 5-12″, with the heaviest south.

The European: Yikes! A solid 11-12″ for the region. You are likely to see this map or something similar on social media outlets today.

BUT! A word of caution.

This is the “operational”, or “deterministic” run of the European. There are 51 “members” of the European Ensemble Model. What’s an ensemble model? A lower resolution version of the “deterministic” model is run 51 times, with each “member” having slightly different initial conditions (pressure, temperature, humidity, etc.) This proves useful because we simply cannot model the atmosphere perfectly. Running a model 51 times, allowing for “wiggle room” in the initial conditions gives us more of a range of possibilities.

Anyway, the mean, or average snow accumulation of those 51 members is significantly lower than the operational…which makes the 11-12″ idea harder to believe. Have a look:

The mean is 5-6″.

So, what’s the bottom line?? I think the low end of the snowfall range will be around 5″. What’s the top end? Not sure yet. Probably somewhere between 8-10″. More to come this afternoon!

This morning was another reminder that sometimes a small amount of snow can be WORSE for road conditions than a few inches….especially if it comes at the wrong time of day. While some places got an inch or so, most locations “only” got a coating, but it came at rush hour and roads got slick in a hurry.

The radar at 9:15am showed the last of the hefty snow bands in Lawrence County, with flurries elsewhere:

It sure was nice to see bare ground before this morning’s snow. The snow cover map does not reflect today’s snow and shows a nice zone of bare ground across the region:

For the rest of the work week, we will be “nickled and dimed” by a few weak systems that can, as this morning’s did, drop small accumulations of snow. Another one will cruise through Wednesday morning and another Thursday. Snowfall amounts with each will generally be under an inch, but watch for “sneaky” bands like we had this morning that can drop locally a bit more.

The BIG story this week? Yup, the COLD. Our 7-day forecast:

We are forecasting the 2nd coldest stretch of weather for these dates since 1930 in Youngstown. Here’s the list of coldest February 25-March 3 periods:

The longer range? It looks ugly through most of the first half of March. The 8-16 day outlook off the Climate Forecast System model shows temperatures much below average for March 4-12:

We have some forecasting challenges ahead for the weekend and early next week. There is likely to be a storm that impacts the Valley sometime in the Sunday-Monday time frame. How big of a storm, what type of precipitation it will bring, if snow….how much…all these things are unclear right now.

If you are seeing web sites/Facebook pages that have scary maps with dramatic headlines and/or are providing SPECIFIC snowfall forecasts a week or more out…STAY AWAY! Stay far, far away.